MoS₂ Nanodonuts for High-Sensitivity Surface-Enhanced Raman Spectroscopy

Area of Science:

• Materials Science
• Nanotechnology
• Spectroscopy

Background:

• Graphene and 2D transition metal dichalcogenides (TMD) nanostructures offer potential for surface-enhanced Raman spectroscopy (SERS).
• The localized surface plasmonic resonance (LSPR) of TMD nanostructures is crucial for SERS enhancement, influenced by their morphology.
• Existing SERS substrates often rely on plasmonic metals, limiting cost-effectiveness and sensitivity.

Purpose of the Study:

• To report the first successful growth of molybdenum disulfide (MoS2) nanodonuts on graphene.
• To investigate the SERS performance of MoS2 nanodonuts/graphene nanohybrids.
• To demonstrate a novel non-metallic SERS substrate with high sensitivity.

Main Methods:

• Vapor transport process for growing MoS2 nanodonuts on graphene.
• Fabrication of MoS2 nanodonuts/graphene nanohybrid SERS substrates.
• Surface-enhanced Raman spectroscopy (SERS) measurements using Rhodamine 6G (R6G) as a probe molecule.
• Finite-difference time-domain (FDTD) simulations to analyze LSPR effects.

Main Results:

• Successfully synthesized MoS2 nanodonuts on graphene substrates.
• Achieved a remarkably high SERS sensitivity for R6G down to 2 × 10^-12 M.
• Demonstrated a more robust LSPR effect in MoS2 nanodonuts compared to other nanostructures like nanodiscs.
• Observed SERS sensitivity one order of magnitude higher than plasmonic metal-based SERS substrates.

Conclusions:

• MoS2 nanodonuts/graphene nanohybrids represent a highly effective non-metallic SERS substrate.
• The unique nanodonut morphology enhances LSPR, leading to superior SERS performance.
• This approach offers a promising pathway for developing high-sensitivity, low-cost biosensing applications.